1. Field of the Invention
The present invention generally relates to electronic design automation. More specifically, the present invention relates to methods and apparatuses for determining a photolithography process model which models the influence of topography variations.
2. Related Art
Rapid advances in computing technology can largely be attributed to improvements in semiconductor manufacturing technologies which have made it possible to integrate tens of millions of devices onto a single chip.
Process models are commonly used to model semiconductor manufacturing processes. A process model can be used in a number of applications during the design of a semiconductor chip. For example, process models are commonly used for making corrections to layouts to compensate for undesirable effects of semiconductor manufacturing processes.
Inaccuracies in the process model can negatively affect the efficacy of applications which use these models. For example, inaccuracies in a photolithography process model can reduce the efficacy of optical proximity correction (OPC). Some photolithography processes use multiple exposure-and-development steps to print the desired features. Conventional process models do not accurately model such photolithography processes. Hence, it is desirable to determine accurate process models for photolithography processes that use multiple exposure-and-development steps.